Concussion: A fuzzy diagnosis

Criteria for concussion diagnosis are heterogeneous and require better definition and diagnostic tools, according to a study published Oct. 2 in the Journal of Neurosurgery.   

The specter of possible short- and long-term consequences of concussive head injuries haunts many athletes. The issue reached the national spotlight again earlier in October after Washington Redskins Quarterback Robert Griffin III returned to practice three days after a concussion.

Legislators have recognized the problem; lawmakers in more than 26 states have passed legislation requiring evaluation of student athletes with concussions prior to returning to sports.

However, the definition of concussion has evolved over time, and various medical specialties rely on different definitions. Thus, accurately identifying which athletes meet diagnostic criteria and require mandated evaluation remains challenging.

Ann-Christine Duhaime, MD, from the department of neurosurgery at Massachusetts General Hospital in Boston, and colleagues sought to analyze the spectrum of clinical presentations used in concussion diagnosis by sports team medical personnel.

The researchers focused on 450 college football and ice hockey players, who wore helmets equipped with Head Impact Telemetry, which measured the frequency, magnitude and location of head impacts, over two to four seasons of play. Athletes underwent pre- and post-season clinical screening, including symptoms, cognition and imaging. Players with a diagnosed concussion underwent the same battery of tests post-concussion.

The researchers recorded 486,594 head impacts and 48 concussions in 44 players. A total of 31 concussions were linked with a specific impact; 17 concussions were not. The most common symptoms were mental clouding, headache and dizziness. Players were usually diagnosed based on various self-reported symptoms. Time to diagnosis ranged from immediate to four days (mean, 23 hours).  

According to Duhaime and colleagues, the specific clinical signs and symptoms used to diagnose concussion may be inadequate and fail to measure the gravity of the injury or predict adverse consequences. In addition, “Current use of return to baseline neurocognitive scores, along with lack of signs or symptoms at rest and exertion, as a gate for return to play has not been validated as an indicator that the various potential risks of adverse consequences from return to play have passed,” wrote Duhaime et al.

The researchers suggested replacing the term 'concussion' with the concept of a concussion spectrum. The shift may help medical personnel determine the range of factors that can influence patient outcomes, according to Duhaime et al.

Brain imaging data have been collected at one of the three universities as part the ongoing larger study but were not used in the current analysis. The current study is part of a larger investigation into the biomechanical basis of concussion and the effects of repeat impacts to the head, conducted over five years at Brown University in Providence, R.I., Dartmouth College in Hanover, N.H. and Virginia Tech in Blacksburg, Va.

Additional research is underway to determine which data—clinical profiles, biomechanical parameters, test scores imaging features or genetic characteristics—best predict patients at risk for adverse consequences from participation in contact sports.

In an email, Duhaime underscored the need for additional research, and wrote, "Even the most sophisticated currently available conventional imaging technologies have not been useful in predicting which patients diagnosed with concussion are at risk for serious outcomes.  It's also uncertain whether any of the experimental imaging technologies currently being developed will be able to provide helpful information."